One of conventional paging systems comprises a plurality of apparatus each producing a paging signal in accordance with a calling signal which is received from a corresponding public switching telephone network. For instance, one of the apparatus covers a nation-wide service zone, and each of the remaining apparatus covers a corresponding one of local service zones. In each of the service zones, a paging signal is radiated from a plurality of antennas of the apparatus so that one of pager receivers each having a fixed receiving signal frequency can receive the paging signal.
According to the conventional paging system, however, frequencies of paging signals for the nationwide service zone must be different from those of paging signals for the local service zones, and the same allocation of frequencies must be performed in two adjacent local service zones having an overlapping service area for the reason why a phasing of those paging signals can not be performed in the service zones. Further, a pager receiver must be replaced by one having another fixed receiving signal frequency in a case where a service zone is changed for a subscriber. As a result, an effective utilization of frequencies can not be realized in the conventional paging system.